1. Field of Inventive Concepts
Present inventive concepts relate to methods for manufacturing semiconductor devices.
2. Description of Related Art
A replacement metal gate (RMG) process may be used in semiconductor device fabrication. For example, a semiconductor device may be manufactured by depositing a high-k metal gate (HKMG) stack in a trench formed by removing a sacrificial gate.
In order to obtain a satisfactory threshold voltage (Vt) in manufacturing a CMOS device, a PMOS gate and an NMOS gate can be formed using two different work function materials. Specifically, the work function of the PMOS gate should be higher than that of the NMOS gate.
For example, a PMOS gate and an NMOS gate may be formed using first and second metal layers having different work functions. In order to form the PMOS gate and the NMOS gate using different metals, a first metal layer is deposited in a PMOS region and an NMOS region, the first metal layer in the NMOS region is removed, and the second metal layer is deposited on the NMOS region. However, in order to prevent/reduce over etch in the course of removing the first metal layer, it may be necessary/useful to attain a sufficiently large etch margin.